# Aortic Stenosis

Aortic stenosis management hinges on confirming hemodynamic severity, resolving low-gradient discordance, and selecting valve replacement modality through anatomy, operative risk, life expectancy, concomitant disease, and transfemoral access.

**Clinical question:** How should physicians confirm severe aortic stenosis and select TAVR, SAVR, surveillance, or palliation?

Updated: 2026-08-21T02:09:20.280704+00:00

## What matters in practice
- Confirm severe AS on transthoracic echocardiography with AVA less than 1.0 cm² plus Vmax at least 4.0 m/s or mean gradient at least 40 mm Hg when measures are concordant.[11][13][14]
- For AVA-gradient discordance, re-evaluate Doppler and LVOT measurements, calculate stroke-volume index and dimensionless index, then use dobutamine stress echocardiography and/or gated noncontrast CT calcium scoring to adjudicate true severity.[12][13][14]
- Valve replacement is directed to confirmed severe AS; low-gradient disease requires confirmation before intervention when AS is the proposed indication.[13]
- TAVR candidacy requires Heart Team review of annular dimensions, coronary anatomy, vascular access, procedural hazards, and the need for concomitant surgical treatment.[1][23]
- In bicuspid AS, SAVR remains particularly appropriate when aortic root dilatation, complex coronary disease, or severe mitral regurgitation requires surgery; randomized TAVR-versus-SAVR trials in bicuspid anatomy are lacking.[21][23]

## Confirm hemodynamic severity on transthoracic echocardiography

Use an integrated Doppler assessment before assigning an intervention pathway.

Obtain transthoracic echocardiography (TTE) as the first-line imaging study. Concordant severe AS is supported by aortic valve area (AVA) less than 1.0 cm² with peak aortic jet velocity (Vmax) at least 4.0 m/s or mean transvalvular gradient at least 40 mm Hg; concordant nonsevere AS is supported by AVA greater than 1.0 cm² with mean gradient below 40 mm Hg or Vmax below 4.0 m/s.[11][13][14]

Do not base severity on auscultation alone. When AVA, Vmax, and mean gradient disagree, first verify acquisition and continuity-equation inputs, particularly LVOT measurement and pulsed-wave versus continuous-wave Doppler placement. Then integrate stroke volume, LVEF, LV hypertrophy, symptoms, valve calcification, and dimensionless index; a dimensionless index of 0.25 or less supports severe stenosis.[12][18]

Classify discordance by flow and LVEF because the next test differs. Low flow is generally identified by stroke-volume index below 35 mL/beat/m²; low-flow, low-gradient AS may occur with reduced LVEF (classical) or preserved LVEF (paradoxical).[12]
- Record AVA, Vmax, mean gradient, stroke-volume index, LVEF, and dimensionless index on the interpretation when results are discordant.[12][13]
- Treat AVA less than 1.0 cm² with Vmax below 4.0 m/s and mean gradient below 40 mm Hg as an adjudication problem rather than automatically as severe AS.[11][13][14]

*TTE patterns that determine the next diagnostic step.[11][12][13][14][18]*

| Pattern | Key findings | Interpretation and next action |
| --- | --- | --- |
| Concordant severe AS | AVA <1.0 cm² and Vmax ≥4.0 m/s or mean gradient ≥40 mm Hg | Severe AS confirmed; evaluate whether valve replacement is indicated and determine procedural strategy.[11][13][14] |
| Classical low-flow, low-gradient AS | AVA <1.0 cm², Vmax <4.0 m/s, mean gradient <40 mm Hg, low stroke volume, reduced LVEF | Use dobutamine stress echocardiography to assess severity if resting measurements are ambiguous; CT calcium scoring can complement adjudication.[11][13] |
| Paradoxical low-flow, low-gradient AS | AVA <1.0 cm², Vmax <4.0 m/s, mean gradient <40 mm Hg, stroke-volume index <35 mL/beat/m² despite preserved LVEF | Recheck measurements and use an integrated assessment including CT valve calcium scoring; low flow can explain discordance.[12][14] |
| Normal-flow low-gradient pattern | AVA <1.0 cm² with Vmax <4.0 m/s and mean gradient <40 mm Hg despite normal flow | Use integrated reassessment of Doppler, dimensionless index, calcification, ventricular phenotype, and symptoms; classification remains more challenging than established low-flow pathways.[12] |

## Resolve low-gradient aortic stenosis before committing to valve replacement

Separate true severe fixed obstruction from low-flow underestimation or measurement error.

In low-flow discordant AS, dobutamine stress echocardiography (DSE) can increase transvalvular flow and reconcile AVA with gradient; it is considered the reference functional test for severity grading in low-flow states. Use caution in advanced cardiomyopathy because dobutamine may provoke or worsen arrhythmias and mitral regurgitation.[11]

A stress AVA below 1.0 cm² has been used to define true severe AS, but DSE may be nondiagnostic when flow reserve is absent or limited; one analysis cited a nondiagnostic rate of approximately 55% in classical low-flow, low-gradient AS. In that setting, noncontrast ECG-gated multislice CT aortic valve calcium scoring provides an anatomic adjudication strategy rather than repeating an indeterminate stress study.[13]

For CT calcium scoring, thresholds supporting severe AS are 2,000 Agatston units in men and 1,200 Agatston units in women. When annular size is unusually small or large, index calcium burden to annular area; reported severe thresholds are 500 AU/cm² in men and 300 AU/cm² in women.[14]

CT calcium burden is not a substitute for careful Doppler review. It should resolve a clinically meaningful uncertainty—whether a patient with symptoms, ventricular dysfunction, or another potential intervention indication truly has severe AS—because valve replacement for low-gradient disease depends on confirmation of severe obstruction.[13][14]
- Use DSE principally for low-flow discordance; do not use it merely to repeat a concordant high-gradient TTE.[11][13]
- Use noncontrast ECG-gated CT calcium scoring when DSE is unavailable, unsafe, or nondiagnostic, while recognizing that CT adjudication is an anatomic complement to functional testing.[13][14]

*Practical adjudication of AVA-gradient discordance.[11][12][13][14]*

| Diagnostic tool | Decision signal | Important limitation or exception |
| --- | --- | --- |
| Repeat integrated TTE | Confirms Doppler alignment, LVOT continuity-equation inputs, stroke volume, and dimensionless index; dimensionless index ≤0.25 supports severe AS.[12][18] | Measurement error can create apparent AVA-gradient discordance.[14] |
| Dobutamine stress echocardiography | Corrects low-flow effects and may establish true severe AS when stress AVA remains <1.0 cm².[11][13] | May worsen arrhythmias or mitral regurgitation; absent or limited flow reserve can make the study nondiagnostic.[11][13] |
| ECG-gated noncontrast CT calcium score | Supports severe AS at ≥2,000 AU in men or ≥1,200 AU in women; use indexed thresholds in markedly abnormal annular size.[14] | Interpret within the full clinical and echocardiographic context rather than as an isolated intervention trigger.[12][14] |

## Refer confirmed severe aortic stenosis for Heart Team valve-replacement planning

The procedure choice is an anatomic and lifetime-management decision, not a generic preference for less invasive treatment.

Once severe AS is confirmed and valve replacement is under consideration, use a multidisciplinary Heart Team to select TAVR versus SAVR. The TAVR device evaluation must address annular fit, vascular access, coronary anatomy, calcification distribution, concurrent cardiac disease, and the patient’s ability to receive antithrombotic therapy.[1][23]

Transfemoral TAVR was compared with surgery in low-surgical-risk severe AS in a randomized trial, establishing that TAVR is an evidence-based replacement option in appropriately selected low-risk patients.[5] TAVR also became a treatment option for patients unsuitable for surgery.[2] Procedure selection should nevertheless account for access feasibility and anatomic hazards rather than operative-risk category alone.[1][23]

SAVR should be favored when associated pathology requires an open surgical approach, including aortic root dilatation, complex coronary disease, or severe mitral regurgitation in the setting of bicuspid AS.[23] For bicuspid anatomy, randomized comparisons of TAVR and SAVR are lacking; observational and propensity-matched data may inform counseling but do not replace anatomy-based surgical assessment.[21][22][23]

Before TAVR, identify device-specific contraindications and access barriers. The SAPIEN 3 labeling excludes patients unable to tolerate antithrombotic medication or with active infection; it also identifies unsuitable annular sizing, heavily diseased or undersized femoral arteries, abnormal access vessels, and large leaflet calcium that could obstruct coronary arteries as procedural concerns.[1]
- Use preprocedural CT-based sizing and access assessment to determine annular compatibility, transfemoral feasibility, and coronary obstruction risk.[1][22]
- Route patients with bicuspid AS plus root disease or surgical coronary/mitral indications toward SAVR planning rather than extrapolating from pivotal tricuspid-valve TAVR trials.[21][23]
- Avoid TAVR during active infection and when antithrombotic therapy cannot be tolerated.[1]

### TAVR-specific risk discussion

Counsel patients that TAVR complications include major vascular complications, stroke, conduction disturbances, coronary artery obstruction, acute kidney injury, and infection.[1][19] Device labeling also identifies contrast exposure, radiation-related skin injury, material hypersensitivity, and thrombotic complications as relevant procedural considerations.[1]
- Use access-vessel anatomy to quantify whether transfemoral delivery is feasible; heavily diseased or small femoral vessels may preclude the delivery system.[1]
- Review leaflet calcium and coronary anatomy when planning TAVR because large calcium deposits may obstruct coronary vessels.[1]

*Features that shift the replacement strategy toward TAVR or SAVR.[1][2][5][21][22][23]*

| Clinical feature | TAVR implication | SAVR implication |
| --- | --- | --- |
| Suitable transfemoral access and compatible annulus | Supports consideration of transfemoral TAVR after Heart Team review.[1][5] | Does not preclude surgery; incorporate other operative and lifetime factors.[23] |
| Inoperable or unsuitable for surgery | TAVR is a therapeutic option for severe AS in this population.[2] | Not applicable when surgery is not feasible.[2] |
| Bicuspid AS with root dilatation, complex coronary disease, or severe mitral regurgitation | TAVR evidence is less definitive because randomized bicuspid comparisons are lacking.[21][23] | SAVR is particularly appropriate when associated disease requires surgery.[23] |
| Active infection or inability to tolerate antithrombotic therapy | SAPIEN 3 TAVR should not be used.[1] | Assess surgical candidacy and infection management separately.[1] |
| Unsuitable femoral vessels or incompatible anatomy | May preclude use of the transfemoral delivery system or increase procedural risk.[1] | SAVR may avoid transfemoral access limitations.[23] |

## Use surveillance or balloon valvuloplasty for defined purposes

Neither medical observation nor valvuloplasty replaces definitive valve replacement for confirmed severe AS when replacement is appropriate.

For patients in whom TTE confirms nonsevere AS or severity remains unconfirmed after adjudication, continue guideline-directed echocardiographic follow-up rather than referring directly for valve replacement.[7][13] Reassess symptoms, ventricular function, Doppler severity, and the development of a discordant low-flow pattern at each clinical change; new uncertainty should trigger repeat integrated TTE and targeted DSE or CT calcium scoring rather than presuming progression.[7][11][12]

Balloon aortic valvuloplasty (BAV) is a palliative procedure for selected elderly patients with symptomatic AS and is not a durable alternative to valve replacement.[3][6] Use it only when a temporary reduction in obstruction has a defined clinical objective, such as palliation or a bridge while candidacy for definitive treatment is clarified; reassess for recurrent limitation and definitive-valve options after the procedure.[3][6]
- Do not use BAV as a substitute for durable valve replacement in a patient who is otherwise a candidate for TAVR or SAVR.[3][6]
- When symptoms and AS severity are discordant, revisit alternative causes and repeat objective hemodynamic assessment before attributing symptoms solely to the valve.[12][13]

*Management when definitive replacement is not immediately performed.[3][6][7][11][13]*

| Scenario | Action | Purpose |
| --- | --- | --- |
| Nonsevere or unresolved AS severity | Serial clinical and TTE follow-up; repeat integrated assessment if symptoms, LVEF, flow, or Doppler findings change.[7][11][12] | Avoid intervention for unconfirmed severe obstruction.[13] |
| Symptomatic selected elderly patient not proceeding directly to replacement | Consider BAV as palliation or a temporary strategy with a defined goal.[3][6] | Temporary symptomatic/hemodynamic relief, not durable replacement.[3][6] |
| Confirmed severe AS with replacement deferred because of anatomic or clinical barriers | Heart Team reassessment of TAVR access, surgical options, infection status, and procedural contraindications.[1][23] | Identify a modifiable barrier or establish a palliative plan.[1][3] |

## References
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13. Adjudication of Low-Flow, Low-Gradient Aortic Stenosis Severity: Dobutamine Stress Echocardiography and MSCT Are Complementary, Not Competitive — www.jacc.org — https://www.jacc.org/doi/10.1016/j.jcmg.2024.04.018
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## Editorial note

Prepared from cited clinical literature using Astra's research workflow. Verify recommendations against current guidance and patient-specific factors.